TRIAC vs 0-10V vs ELV dimming compatibility
Most LED dimming complaints — flicker, buzzing, lights that drop out at the bottom of the range — come from a mismatch between dimmer, driver and fixture. Here is how the three systems differ and how to pair them.
An LED that flickers, buzzes or shuts off before the dimmer reaches the bottom is almost never a faulty fixture. It is a mismatch between three things that have to agree: the dimmer, the driver, and the fixture itself.
The three systems
TRIAC (forward phase)
TRIAC dimming chops the leading edge off the AC waveform. It is the same technology that dimmed incandescent bulbs, which is why it dominates residential work — the wiring is a standard two-wire switch leg with no extra conductors.
Use it for: residential potlights, retrofit work where you are reusing existing switch wiring, and any fixture whose driver is marked TRIAC or phase dimmable. Most of our residential slim panels are TRIAC dimmable.
Watch for: a minimum load. A TRIAC dimmer rated for incandescent may need more load than three LED potlights present, which produces flicker or a dead bottom end. Use a dimmer specifically rated for LED and check its minimum load against your fixture count.
0-10V
0-10V runs a separate pair of low-voltage control wires to the driver. Zero volts is minimum output, ten volts is full. Because the control signal is independent of the power feed, it dims deeply and smoothly and is the standard for commercial work.
Use it for: high bays, troffers, linear fixtures, panels, anything on a lighting control system or connected to occupancy sensing. Our linear high bays and UFO high bays are commonly specified this way.
Watch for: the extra conductors. If the control pair was not pulled during rough-in, 0-10V is not available to you without opening the ceiling — decide before the walls close.
ELV (reverse phase)
ELV, or electronic low voltage, chops the trailing edge instead of the leading edge. It is gentler on electronic drivers and generally produces smoother low-end dimming and less audible buzz than TRIAC.
Use it for: electronic low-voltage transformers, LED tape driven by an electronic driver, and premium residential work where dimming quality is being judged.
Watch for: ELV dimmers are not interchangeable with TRIAC ones. Fitting the wrong type is a common cause of buzzing, and in some combinations it will damage the driver.
Matching them up
| TRIAC | Residential, retrofit, two-wire switch legs. Check minimum load. |
|---|---|
| 0-10V | Commercial, high bay, controls and sensors. Needs a control pair pulled. |
| ELV | Electronic low-voltage drivers, LED tape, smooth low-end residential dimming. |
The three failures and what causes them
- Flicker at low output — usually a dimmer whose minimum load exceeds the connected LED load, or a driver not rated for the dimmer type. Add load, or change to an LED-rated dimmer.
- Audible buzz — commonly a forward-phase dimmer on a driver that wants reverse phase. Try ELV.
- Drops out before the bottom — the driver's minimum dimming level is higher than the dimmer's. A driver specified to 1% will go lower than one specified to 10%; this is a datasheet number, not something to solve on site.
Low-voltage tape is a separate decision
With LED strip lighting the dimming happens at the driver, not at the tape. A non-dimmable driver cannot be dimmed no matter what switch you install. Choose the driver first — our low-voltage drivers and transformers are listed as TRIAC dimmable or non-dimmable, and the 30W 12VDC TRIAC-dimmable Class 2 driver is a common choice for residential runs.
Size the driver to the run as well: total the tape's watts per metre across the full length and leave headroom rather than loading a driver to its limit.
Before you order
Read the fixture's dimming specification and buy the dimmer to match, not the other way round. Where the manufacturer publishes a compatibility list, use it — it is the only reliable guide. Browse LED dimmer switches for LED-rated options.
Check before you install. This guide summarises common practice to help you specify parts. The Ontario Building Code, the Ontario Fire Code and the Canadian Electrical Code are the authority, they are revised periodically, and your local authority having jurisdiction can be stricter. Confirm current requirements and have the work done by a licensed electrician.
Common questions
- Why do my LED potlights flicker when dimmed?
- Most often the dimmer's minimum load is higher than the LED load connected to it, or the driver is not rated for that dimmer type. Use a dimmer specifically rated for LED and check its minimum load against your fixture count.
- Can I use a TRIAC dimmer with a 0-10V fixture?
- No. 0-10V dimming needs a separate pair of low-voltage control wires run to the driver. If that pair was not pulled during rough-in, 0-10V is not available without opening the ceiling.
- What is the difference between TRIAC and ELV dimming?
- TRIAC is forward phase — it chops the leading edge of the AC waveform. ELV is reverse phase and chops the trailing edge, which is gentler on electronic drivers and usually gives smoother low-end dimming with less buzz.
- Why won't my LED strip lights dim?
- With low-voltage tape the dimming happens at the driver. If the driver is non-dimmable, no switch will dim it. Check the driver's specification and replace it with a dimmable model rated for your dimmer type.